22. A marker line H-126, carries a genetic factor making
chiorophyl mutation variagated
M. MAEKAWA, K. Rikishi, T. MATSIJURA and K. NODA
Research Institute for Bioresources, Okayama University,
Kurashiki, 710-0046 Japan
Genetic variegations not controlled
by cytoplasmic inheritance are often conferred by the excision of a DNA
transposable element. The genetic analysis of a variegated mutant could
lead to the first finding of a DNA transposable element that can transpose
in intact rice genome. A variegated yellow leaf (yl) mutant was obtained
spontaneously in F2 of the cross between an indica native variety C-5052
and ajaponica marker line H-126. This mutant segregates variegated and
stable phenotyptes. We produced a near isogenic line (NIL) showing stable
yellow leaf (yl-stb) with the genetic background of the japonica variety
Taichung 65 (T-65). In order to reveal the genetic factor(s) responsible
for the variegation of the yellow leaf mutant, we conducted genetic analysis
in the pmgenies from crosses of the yl-stb NIL with several marker lines,
C-5052 and H-126. As shown in Table 1, T-65 yl-stb BC3F1 and BC4F1 plants
segregate yl-v (yl-variegated) plants with frequencies of 1.7 and 0.9 %,
respectively. However, all the yl-v plants that appeared in the BC3F2 and
BC4F2 are vague in variegation seen only in a leaf. Near isogenic lines
of yl-stb were produced from BC3F2 and BC4F2 plants. The F2 populations
from crosses between T-65 yl-stb BC3F2 or BC4F2 plant and marker lines
excepting those from the cross, H-126 x T-65 yl-stb BC4F2 plant, segregate
normal and yl-stb plants. Contrary, the cross, H-126 x T-65 yl-stb BC4F2
plant, produced yl-v plants in addition to normal and yl-stb plants. All
the yl-v plants of this cross showed clear variegations in many leaves.
The frequency of yl-v to yl plants (yl-stb and yl-v) was 77.4%, suggesting
that H-126 carries a dominant factor responsible for the variegation. Maekawa
et al. (1998) reported that a variegated albino mutant (al-v) was obtained
in the selfed progenies of revertants of yl-v plants. This suggests that
the variegated albino might be caused by the same factor(s) as that for
the variegated yl. In order to examine this point, an al-v plant was crossed
with T-65 yl-stb BC4F2 plant. As shown in Table 2, two of four Fl plants
segregated both al-v and yl-v with averaged frequencies of 70%. The other
Fls did not segregate any variegated plants. This result indicates that
al-v and yl-v are controlled by the same genetic factor. Accordingly, the
genetic factor conferring variegation on albino and yellow leaves is surmised
to be derived from H-126.
Maekawa, M., 1995. Irregular segregation of variegated chlorophyll
deficiency derived from a cross between distantly related varieties in
Oryza sativa L.. In Modification of Gene Expression and Non-Mendelian Inheritance,
K. Oono and F. Takaiwa (eds.). MAR, Japan, p. 379-388.
Maekawa, M., T. Rikiishi, T. Malsuura and K. Noda, 1998.
A gene for variegated albino linked to Ig on chromosome 4. RON 15: 107-108.
|